A 2008 policy had symbolic value only, researchers say.

Action Points

Note that this observational study found that a "fast food ban" in areas of Los Angeles did not result in a reduction in obesity rates.

Be aware that the "ban" was hindered by a variety of provisions and loopholes resulting in a largely unchanged food landscape in the areas of interest.

A controversial "fast food ban" in some of the poorest neighborhoods in Los Angeles, enacted in 2008, has had little impact on the health or weight of the residents there after 7 years, researchers said.

The ordinance -- which didn't ban all fast-food sales, but rather restricted the opening or remodeling of certain stand-alone restaurants -- was an attempt to improve health outcomes and lower obesity rates among the 700,000 residents living in the affected areas.

But survey data on body weight and dietary composition through 2012 indicated that the ordinance had no detectable effect, said economist Roland Sturm, PhD, of the RAND Corporation, and colleague Aiko Hattori, of the University of North Carolina. Their findings were published in Social Science & Medicine.

"The South Los Angeles fast food ban may have symbolic value, but it has had no measurable impact in improving diets or reducing obesity," said Sturm. "This should not come as a surprise: Most food outlets in the area are small food stores or small restaurants with limited seating that are not affected by the policy."

The only positive development in the affected neighborhoods -- a drop in soft drink consumption, which began in 2007 -- was similar to the changes in other areas of Los Angeles.

The researchers tracked the opening of new fast food establishments by looking at permits. Diet and obesity measures came from three waves of the California Health Interview Survey (CHIS), a randomized telephone survey in 2007, 2009, 2011, and 2012. Pregnant women, residents who lived in an area defined as rural, and those whose information was reported by another person were excluded.

In the survey, measurements of diet were taken, and body mass index was calculated from self-reported height and weight. Respondents were split into two groups: the intervention group in the area of the fast-food ban (n=467 in 2007, 483 in 2009, and 535 in 2011-12), and the comparison group in other parts of Los Angeles (n=3,829 in 2007, 2,920 in 2009, and 3,034 in 2011-12) or living in other parts of Los Angeles County (n=11,591 in 2007, 8,377 in 2009, and 8,252 in 2011-12).

Sturm and Hattori found that the only difference between new food outlets in the two areas was that a new retail opening in the regulation area was more likely to be a small food or convenience store, while outside the area a larger independent restaurant was more likely.

"The food environment is not changing differentially but rather than the composition of new retail outlets mirrors the existing food environment," wrote the researchers. No new stand-alone fast food restaurants opened, but fast food restaurants opened in shared spaces, and the rate of new fast food chain restaurants was the same in both areas. About 10% of the food establishments in all areas were new.

As for the health of the residents, according to the survey, obesity and being overweight increased in all areas from 2007 to 2012, and the increase was significantly greater in the regulated area. Consumption of what was defined as "fast food" increased in all areas.

In the regulated area, the rate of obesity and average BMI were higher than in other parts of the city, a gap that widened until 2012.

"Despite a vigorous debate of policy interventions to change food environments, very few identifiable policies have been implemented," noted the authors. "We do not believe that changes in the food environment due to the regulation could have had a meaningful impact on dietary choices in South LA."

Limitations of the study included the reliance on a survey for health outcomes and a relatively small sample size. In addition, measuring restaurant environments over time is difficult because some of the tools used to do it have limited accuracy.

The researchers wrote that there may be another reason why targeting free-standing fast food restaurants might not be effective. "Free-standing fast food restaurants tend to be located on major roads, primarily catering to customers who drive, or, as for drive-through windows, exclusively cater to drivers," they wrote. "In that case, neighborhood food environments may not be as strongly associated with dietary intake or obesity."